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  1. Ken Buesseler on March 8, 2021 at 3:05 pm

    You note a detection limit of 0.1 Bq/L (100 Bq/m3) for 137Cs in 2L samples. So to get to 1-2 Bq/m3, which is the 137Cs level in most of the ocean, you would need 100-200 L samples? Have you tried to measure 137Cs and 135Cs at these more common and much lower levels. Alternatively, could we measure 137Cs via gamma methods, and 135Cs via ICPMS with more sensitivity, or would you still need 100+ L if 137Cs is only 1-2 Bq/m3?

  2. Jian Zheng on March 8, 2021 at 8:13 pm

    Based on the sensitivity of our analytical system, we need 50-100L samples to measure 137Cs and 135Cs in common level seawater (1-2 Bq/m3). As the atom ratio of 135Cs/137Cs is about 0.3, 50 L is necessary for 137Cs and 135Cs measurement. Of course, 137Cs can be measured by gamma method, but for 135Cs, large volume sample is required for our ICP-MS/MS technique. The main challenge is to remove the seawater matrix (Na, K, Rb, Ga, Mg etc) from Cs. We are currently working on this issue…